1. Field of the Invention
This invention relates to front restraint devices for securing articles, e.g., glass sheets, automotive backlites, automotive windshields or automotive sidelights, in an article shipping bin.
2. Discussion of the Technical Problems
Articles, e.g., glass sheets, automotive backlites, automotive windshields, or automotive sidelights, are normally shipped to automotive manufacturers in bins or racks.
During shipment, e.g., by rail car or truck, the articles in the bins are subjected to transportation forces. For example, the articles are subjected to (1) longitudinal forces which act to move the articles toward and away from the sidewalls of the bin, i.e., along a longitudinal reciprocating path; (2) oscillatory forces which tend to move the articles about a pivot point toward and away from the back wall of the bin, i.e., along the oscillatory reciprocating path; and (3) lateral forces which tend to move the articles toward and away from the back wall of the bin, i.e., along a lateral reciprocating path.
These forces which act on the articles are caused by the motion of the rail car or truck as it moves along the rails or road, respectively. As can be appreciated by those skilled in the art, these longitudinal, oscillatory and lateral forces can damage the articles during transit making them unusable.
In general, to prevent damage to the articles, e.g., automotive backlites, during shipping, the backlites are normally loaded in a bin in a vertical position with an edge of the backlites resting on a resilient pad and tilted toward the back wall of the bin for packing stability. The tilting of the backlites facilitates loading of the backlites into the bin and also tends to reduce the oscillatory motion of the backlites during shipment. More particularly, because the articles are on one edge tilted toward the back wall, a greater force has to be applied to oscillate the backlites about the bottom edge thereby canceling out small swaying motions of the rail car or truck.
In the prior art, bins used for transporting automotive backlites are provided with a wedged shaped member positioned in the back of the bin to provide a tilt to the backlites. This is undesirable for several reasons; namely, (1) when the bin is unloaded, the wedged shaped member has to be disposed of creating a solid waste problem; and (2) for partial loads and different curvature of backlites, it is requiredto have on hand different shaped wedge members thereby requiring different members to be made and stored.
To minimize and/or cancel longitudinal forces of the backlites during transit, dunnage, e.g., pieces of wood and corrigated cardboard are secured between the sides of the backlites and the sidewalls of the bin. This is undesirable because (1) after the bin is unloaded, the dunnage has to be disposed of creating a solid waste problem; and (2) the dunnage becomes compressed during transit by the longitudinal forces moving the sides of the backlites against the dunnage thereby increasing the longitudinal reciprocating path. Especially in the instance where the articles are untempered glass increasing the longitudinal reciprocating path moves the articles along an increased longitudinal reciprocating path thereby increasing the probability of damaging the sides of the articles.
The prior art practice to prevent or minimize oscillatory and lateral forces acting on the backlites during transit is to secure the backlites in the bin against the back wall with webbing or steel bands. During transit, the oscillatory and lateral forces of the backlites stretch the bands and webbing which can cause the backlites to fall out of the bin. Further, when the webbing and steel bands stretch, the oscillatory and lateral reciprocating paths increase. In the instance where the articles are untempered glass, this causes individual articles to have individual oscillatory paths and frequencies instead of the articles acting as a unitized pack. When this occurs, the articles slam against each which can damage the articles. When the oscillatory and lateral paths increase and the articles act as a unitized pack, the outermost articles are subjected to increased forces and are damaged. Further, applying and removing the webbing or steel bands is time consuming and still further, disposing of the steel bands creates a solid waste disposal problem.
There are available systems for eliminating the webbing and steel bands but these systems have limitations. For example, disclosed in U.S. Patent Application Ser. No. 371,912 filed June 20, 1973, in the name of James R. Rowley and Walter E. Pater and entitled "Method of and Device for Restraining Movement of Articles During Transit" now U.S. Pat. No. 3,995,738 there is disclosed a front restraint system that eliminates webbing and steel bands. In general, a plurality of upper pads and a plurality of lower pads are provided on a generally H-shaped member. After the articles, e.g., automotive windshields are loaded in a rack, the pads are moved into locking engaging with the articles. Oscillatory forces acting on the upper pads are damaged by the pivoting action of the upper and lower pads. Although the device of the above-identified application is ideally suitable for shipping automotive windshields, it is expensive to construct and use. It is expensive to use because each of the four pads has to be moved into engagement with the articles and thereafter locked in position.
It would be advantageous, therefore, if a bin for shipping articles were available that did not have the drawbacks or limitations of the prior art. More particularly, it would be advantageous to provide a bin with (1) a front restraint system that is economical to construct and use; and does not have the drawbacks of steel bonds and webbing; (2) an end restraint system; and (3) an adjustable back support that eliminates the solid waste problems.